<VV> Re: Rod bearing wear

[djtcz at comcast.net]

I would not spend 10 seconds worrying about bearing materials, oils, additives, or "lugging" the engine with tall gearing.

 Down to/through the copper in 27,000 miles is quick, but I'd have expected a gross journal roundness or size error to make itself known much quicker (maybe within minutes after starting, or during the first high speed run).  I'd actually expect that much bearing wear to start the warm oil pressure to dropping.

Was the crank ground and re-tufftrided? Regardless, Who polished it? 
A local heat treater warned me a long time ago to be sure and polish a tuff-trided crank in the operating direction.  Since then the recommendation has appeared more and more.

Any measuring or plasti-gaging done? 

Had you loaned the car to someone recently, or had the oil changed by someone?

Not knowing the pressure history makes any guess just a guess.

bearing failure troubleshooting guide here. 
http://www.engineparts.com/motorhead/techstuff/bearingfailures.htm

Note the difference in smoothness and length of the worn surface between "normal" and accelerated.

Lets Assume for a moment, and strictly for the sake of argument, lubrication was adequate (since without a pressure history the lubrication situation is unknown, and a mystery).  Under "accelerated wear" they focus on journal surface finish a lot, and say this - "Wear in the presence of adequate lubrication to prevent heat build-up and wiping is caused by peaks in the journal surface finish profile which penetrate the oil film and abrade the bearing. Always grind opposite to rotation and polish in the direction of rotation. "


> I haven't totally fixed the spam problem yet, but I wanted to get some 
> opinions about rod bearings. My basic question is why did they wear out so 
> fast in my engine? 
> 
> My 140 is about 4 years & 27,000 miles since complete o'haul (NOS 
> pistons/cyl, rods balanced, crank checked & turned as necessary, heads & 
> seats checked, new guides & seats as necessary. I broke it in with regular 
> oil & at 500 miles changed to synthetic (Amsoil). It has been driven almost 
> entirely on the freeway (last 4 conventions). I do drive hard (I use my 
> secondaries a lot!), but never when cold and I use 5,000 as reline. In 
> fact, with my 14" wheels/tires & 327 gears, I am usually cruising at least 
> 1,000 rpm lower than most others. It does sit, however, for at least a 
> month at a time between starts, but I never let it go above 1,500 when I 
> start it until it runs for a few minutes. " Is there a difference in coating that could be causing this? 
> Could the bearings we get from one vendor vs. another be different- & cause 
> different wear? I was told that some people (racers?) coat their bearings 
> with a Moly coating to help reduce friction. Could I be having an oil 
> pressure problem, delaying oil to the rods on start-up, or during use? I am 
> thinking maybe I need to install an oil pressure gauge. Any thoughts? 
> 
> David Brown